So Apple has complete control over the distribution mechanism, but zero ability (apart from metadata including the originating company and the target device) to examine the content passing through. Game over? I don’t think so.

Apple can still use its unique role as the center of all things iOS to devise a system through which they would themselves be virtually subscribed to all unremarkable notifications from a particular app’s developer. Think about the worst notification spam you’ve seen. In my experience it’s not super-personalized. In fact, it’s liable to be an inducement to keep using the app, to advance in a game, to become more engaged, etc. I think Apple would collect a ton of useful information about spammy developers if they simply arranged that every app on the App Store that is capable of sending push notifications included, among its list of registered devices, a “pseudo-device” in Cupertino whose sole purpose was to receive notifications, scan them for spammy keywords, apply Bayesian filters, and flag questionable developers.